Diagrams are often used to facilitate communication and understanding in various domains of interests.
In the present disclosure a “diagram” or a “model” is a visual illustration adhering a grammar of a modeling language. The grammar may be formal or informal, and the diagram may loosely adhere to it. Such modeling languages may be specified as a combination of the concrete syntax (i.e., graphical symbols), the abstract syntax (i.e., linguistic constructs), and a set of rules.
Model authors choose their notations from an arbitrary set of graphic symbols. However, some notations are often used for the same purpose. For example, a symbol of a cloud may often be used to represent the Internet, and thus when people view a model and see a cloud they may infer that it represents the Internet without having to review the legend or associated text.